Studies on collectors in which a carbonaceous conductive material is applied on a metal foil such as an aluminum foil or a copper foil to be used as a substrate of an electrode for a secondary battery have been hitherto conducted in various research institutes. Also, a large number of patent applications have been filed and, for example, Patent Documents 1 to 4 are exemplified.
Patent Documents 1 and 2 describe collectors in which a film composed of carbon fine particles that are conductive materials and a film-forming compound is formed on the surface of a substrate such as an aluminum foil or a copper foil. Moreover, Patent Document 3 describes a collector in which a conductive layer composed of a carbon powder (conductive material) and a binder is placed between active materials. Further, Patent Document 4 describes a collector in which a conductive coating layer containing carbon as a conductive agent (conductive material) is placed on the surface. In these, internal resistance of batteries using these collectors is reduced by reducing contact resistance between the collectors and active material layers formed thereon, and thus it has been intended to improve high-speed charge-discharge characteristics and cycle characteristics of the batteries.